Here's how it works: You take 12 large, compound bodyweight exercises (think: squats, push-ups, lunges). Next, you string them together in a circuit so that you don’t hit the same muscle group twice in a row. (This is why you’d put push-ups between squats and lunges, for instance.) Then it’s time to perform the first exercise with all-out effort for 30 seconds, rest for 10, and then hop to the second exercise. Once you get through the 12th move, seven minutes are up and your work is done.

With a workout like this, you get back what you put in—which means you have to put in a lot of work.

Seven minutes sounds easy, right? Well, it shouldn’t be. The effectiveness of any short and sweet workout, this one included, hinges on your ability to push yourself to the absolute brink during every single rep, David Thomas, Ph.D., professor of kinesiology and recreation at Illinois State University, tells SELF. And, honestly, that’s not something most people are willing to do—not because of laziness, but because working at that intensity is really, really, really hard. The saying “Your mind will quit 100 times before your body will” totally applies here. You need to push through a good 99 of those times to really get the benefits advertised with this and other HIIT protocols, burning more calories and building lean muscle in minimal time.

That’s because when you go all out and then give yourself a short time to recover, you’re simultaneously tapping your body’s aerobic and anaerobic (a.k.a. phosphagen and glycolitic) energy systems, Thomas explains. Translation: You get both cardio and strength benefits and in less time than if you performed a dedicated strength workout followed by a separate low- to moderate-intensity cardio workout such as running, Minnesota-based exercise physiologist Mike T. Nelson, Ph.D., C.S.C.S., tells SELF.

You can also burn more calories per minute during your workout as well as afterward, thanks to a process called excess post-exercise oxygen consumption (EPOC), more commonly known as the afterburn effect. The harder you hit it, the harder your aerobic system has to work; you have to take in oxygen at a higher rate than you would at rest as your entire body works to return to its resting state, so you continue burning calories even after you stop moving.

What counts as high enough intensity? While it largely depends on your current fitness levels, most experts put it at roughly 85 percent or more of your VO2 max—the peak amount of oxygen that you’re able to take in and use in a minute. Basically, when performing a seven-minute-long interval workout, you should be huffing, puffing, and pretty much unable to go for seven minutes and one second. (FYI, if you have any existing health conditions or heart problems, speak with your doctor before starting an intense workout regimen like this that stresses the heart.)

Even if you do give it your all for 7 minutes, the workout still has its limitations.

OK, so let’s assume that you’re one of the few people who, when given a high-intensity workout like the 7-Minute Workout, can actually go balls to the wall—and, most important, can do it without sacrificing form. (Safety first!) What kind of benefits can you expect to get then?

Probably fewer than you’d hope. After all, when 7-Minute Workout creator Chris Jordan, M.S., C.S.C.S., director of exercise physiology at the Human Performance Institute in Orlando, co-authored the original seven-minute-long workout in a 2013 ACSM's Health & Fitness Journal article, he never actually said, “We put people on a seven-minute circuit routine and here’s what we found.”

Rather, he looked at what previous research had found and then used that information to try to squeeze current exercise recommendations—150 minutes per week of moderate-intensity aerobic exercise or 75 minutes per week of high-intensity aerobic exercise, plus two or more days per week of muscle-strengthening activities that work all major muscle groups—into as little time as possible.

That’s totally cool, but, unfortunately, the research that the workout is based on isn’t all that applicable. For instance, the only circuit-training study that the article does reference, which is now a good 25 years old, not only incorporated added weights (not just bodyweight moves), it also used a high-intensity circuit protocol that was 40 minutes long…definitely longer than the seven minutes prescribed. (That said, the original article does note that you can repeat the entire circuit two to three times, which would add to the workout’s length and your potential benefits.)

So, for argument’s sake, if you apply that to the 7-Minute Workout, that would work out to 105 calories burned. Definitely not shabby, but probably more than what, if you’re hoping to burn fat and gain lean muscle mass, you’d like.

Still, that’s not to say the 7-Minute Workout—or any short and sweet interval workout—is without benefits.

If you’re either crazy fit and able to push it for seven minutes like none other or if, on the flip side, you’re starting from zero and just want to start doing something, you’ll likely see some cardio benefits, Thomas says. You may find taking the stairs is a little bit easier, and if you stick with it for a good month or so, you may even lose a couple of pounds and build some muscle while you’re at it.

But ultimately, the benefits are limited by not only the workout’s time constraints but also by your own body weight. "It’s really hard to progress a bodyweight workout like this in a significant way,” Nelson says. Sure, you can progress from incline to regular to decline push-ups, but at some point, that push-up just isn’t getting harder and you aren’t going to continue stimulating change, he says.

What’s more, since you likely won’t approach your one-rep max (the most weight you can move for one rep) during the 7-Minute Workout, you won’t do a ton to improve your muscular strength or size, Holly Perkins, C.S.C.S., author of Lift to Get Lean, tells SELF. Rather, you’ll improve your muscular endurance—which is helpful for endurance activities like distance running, cross-country skiing, obstacle races, and rowing, but isn't going to help you get bigger muscles or become stronger.

At the end of the day, the 7-Minute Workout is great to have on hand for days you're short on time, but it shouldn't replace all other workouts.

“The 7-Minute Workout is not a fitness program, it’s a tool,” Perkins says. “To get the most out of it, use it that way.”

Yeah, the 7-Minute Workout does work your cardiovascular system, but you still need to do other types of workouts, like moderate-intensity cardio, to train your body in other ways. “There are multiple components of well-rounded fitness, and you need to hit them all,” Perkins says. Training strength, flexibility, cardiovascular endurance, aerobic power, and muscular endurance are all important for improving fitness and health. The 7-Minute Workout is great at hitting the last two, but for optimal benefits, you need to integrate it into a routine that checks off all of those boxes.

For instance, on days that prioritize heavy strength training, this workout can be a great metabolic finisher. Also called exercise finishers, these are short, high-intensity workouts placed at (yep, you guessed it) the end of your workouts to empty the tank, so to speak, and make sure that you leave nothing on the gym floor. The result: You get your heart rate up, elevate your after-burn, and get more out of every workout.

Meanwhile, on those days when you legit don’t have more than seven minutes to devote to your workout, go ahead and fire up the 7-Minute Workout app. Remember, something is always better than nothing. And when time is tight, high intensity is your best bet.

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